Re-evaluation Decision RVD2022-14, Dazomet and Its Associated End-use Products, Used as a Preservative in Paints, Coatings and Related Uses

Pest Management Regulatory Agency
8 December 2022
ISSN: 1925-1025 (PDF version)
Catalogue number: H113-28/2022-14E-PDF (PDF version)

Summary

Table of contents

• Re-evaluation decision for dazomet and associated end use products, used as a preservative in paints, coatings and related uses
• Re-evaluation decision for dazomet (used as preservatives in paints, coatings and related uses)
• Risk mitigation measures
• Next steps
• Other information
• Evaluation Approach
• Appendix I - Registered material preservative products containing dazomet in Canada as of 6 September 2022

Re-evaluation decision for dazomet and associated end use products, used as a preservative in paints, coatings and related uses

Under the authority of the Pest Control Products Act, all registered pesticides must be re-evaluated by Health Canada's Pest Management Regulatory Agency (PMRA), on behalf of the Minister of Health, to ensure that they continue to have acceptable risk to human health and the environment, and have acceptable value. The re-evaluation considers available data and information^{Footnote 1} from pesticide registrants, published scientific reports, existing assessments, other governments, and international regulatory authorities, as well as comments received during public consultations. Health Canada applies internationally accepted current risk assessment methods as well as risk management approaches and policies. More details, on the legislative framework, risk assessment and risk management approach, are provided underEvaluation Approach.

This document forms part of a re-evaluation assessment of several active ingredients used as preservatives in paints, coatings and related uses. As per Re-evaluation Note REV2018-02, Approach for the Re-Evaluation of Pesticides Used as Preservatives in Paints, Coatings and Related Uses, the paint-related uses of sodium omadine, chlorothalonil, dazomet, folpet and ziram were evaluated separately from other uses and relied on data provided by the registrants and the Antimicrobial Exposure Assessment Task Force II (AEATF II). This approach was adopted in order to obtain and review paint-related studies, have risk assessments more reflective of current and realistic exposure scenarios and to allow for a consistent approach to the risk assessment and risk management for these uses. In the absence of scenario-specific data, paint studies/data were used as surrogates for the assessment of building materials and adhesives.

Dazomet is an "in-can" material preservative against bacterial and fungal contamination or spoilage of adhesives, adhesive coatings, latex paints, aqueous emulsions, coatings, slurries, paper, paper coatings, concrete admixtures and high viscosity suspensions. All other registered uses of dazomet (that is, as a non-selective pre-plant soil fumigant and a slimicide in industrial process fluids (for example, pulp and paper mills, recirculating water cooling towers, industrial air washers and oilfield industry)) were evaluated separately (Re-evaluation Decision RVD2018-34, Dazomet and Its Associated End-use Products). Currently registered products for use as a material preservative containing dazomet can be found in the Pesticide Product Information Database and in Appendix I.

The Proposed Re-evaluation Decision PRVD2020-07, Dazomet and Its Associated End-use Products, Used as a Preservative in Paints, Coatings and Related Uses containing the evaluation of the material preservative uses of dazomet and proposed decision, was published on 9 July 2020 for a 90-day consultation period.

An additional 60 days for consultation^{Footnote 2} was provided in response to requests from stakeholders to accommodate time constraints imposed by pandemic measures; the 150-day consultation period ended on 6 December 2020.

PRVD2020-07 proposed mitigation measures for primary handlers (that is, closed transfer system for liquid formulations; additional personal protective equipment (PPE) for handling all solid formulations; a reduction in amount handled per person per day for soluble and wettable powders; and cancellation of the paper and paper coatings uses) and for secondary professional handlers (that is, reduction in the maximum rate of dazomet for all uses and additional PPE for professional painters using an airless sprayer, coupled with a product stewardship/outreach program).

Health Canada received comments relating to the health and value assessments during the public consultation period conducted in accordance with section 28 of the Pest Control Products Act. Commenters are listed in Appendix II of RVD2022-14. These comments are summarized in Appendix III of RVD2022-14 along with the responses by Health Canada. These comments resulted in a revision to the occupational risk assessment (see Science Evaluation Update of RVD2022-14) and resulted in a change to the proposed re-evaluation decision as described in PRVD2020-07.

A reference list of information used as the basis for the proposed re-evaluation decision is included in PRVD2020-07; no further information was used in the final re-evaluation decision. Therefore, the complete reference list of all information used in this final re-evaluation decision is set out in PRVD2020-07.

This document (Re-evaluation Decision RVD2022-14, Dazomet and Its Associated End-use Products, Used as a Preservative in Paints, Coatings and Related Uses) presents the final re-evaluation decision^{Footnote 3} for the material preservative uses of dazomet, including the required amendments (risk mitigation measures) to protect human health, as well as label amendments required to bring labels to current standards. All products containing dazomet for use as a material preservative that are registered in Canada are subject to this re-evaluation decision.

Re-evaluation decision for dazomet (used as preservatives in paints, coatings and related uses)

Health Canada has completed the re-evaluation of dazomet (used as preservatives in paints, coatings and related uses). Under the authority of the Pest Control Products Act, Health Canada has determined that continued registration of products containing dazomet is acceptable with mitigation measures. An evaluation of available scientific information found that most material preservative uses of dazomet meet current standards for protection of human health and have acceptable value when used according to revised conditions of registration, which includes new mitigation measures. Environmental exposure from the use of dazomet as a material preservative is expected to be minimal.

The uses of dazomet in paper and paper coatings are cancelled since health risks were not shown to be acceptable when used according to the current conditions of registration, or when additional mitigation is considered. Label amendments, as summarized below and listed in Appendix V of RVD2022-14, are required.

Risk mitigation measures

Registered pesticide product labels include specific directions for use. Directions include risk mitigation measures to protect human health and the environment and must be followed by law. The required amendments, including any revised/updated label statements and/or mitigation measures, as a result of the re-evaluation of dazomet, are summarized below. Refer to Appendix V of RVD2022-14 for details.

Human health – Risk Mitigation

To mitigate risks to primary (industrial manufacturers) and/or secondary (professional) handlers:

• Cancellation of the paper and paper coatings uses
  • these uses will be removed from product labels through amendment
• Reduction of maximum label rates for all other uses to 0.53 g a.i./kg product.

To mitigate risks to primary handlers (industrial manufacturers):

• For commercial-class solid products (wettable powder, soluble powder and granular):
  • Additional personal protective equipment (chemical-resistant coveralls over a long-sleeved shirt, long pants, chemical-resistant gloves, socks and chemical-resistant footwear, eye protection (goggles or a faceshield) and a respirator) when mixing/loading; and
  • Reduction in the amount of active ingredient handled per worker per day for wettable powder and soluble powder formulations to 3.36 kg a.i./person/day
• For commercial-class liquid products (solutions/suspensions/emulsifiable concentrates):
  • Open transfer systems when workers handle up to and including 1.12 kg a.i./person/day.
  • Closed transfer systems when workers handle more than 1.12 kg a.i./person/day.

To mitigate risks to professional painters using an airless sprayer:

• Require additional protective equipment (cotton coveralls over a long-sleeved shirt and long pants, chemical-resistant gloves, a painter's hat, and a respirator with a NIOSH-approved organic-vapour-removing cartridge with a prefilter approved for pesticides, or a NIOSH-approved canister approved for pesticides.)

Implementation of product stewardship/outreach plan for paint use.

Next steps

Pest control products requiring label amendments

To comply with this decision, the required amendments (mitigation measures and label updates) must be implemented on all product labels no later than 24 months after the publication date of RVD2022-14. Accordingly, both registrants and retailers will have up to 24 months from the publication date of RVD2022-14 to transition to selling the product with the newly amended labels. Similarly, users will also have the same 24-month period from the date of RVD2022-14 to transition to using products with the newly amended labels, which will be available on the Public Registry. This 24-month period also applies to the requirement that manufactured paint products containing the preservative dazomet must be labelled with the stipulation that professional painters wear personal protective equipment when using an airless sprayer (refer to Appendix V of RVD2022-14).

Health Canada has determined that the identified risks from the use of dazomet as a material preservative under the current conditions of use were from longer-term exposure durations and therefore, the potential risks to human health are considered acceptable during the 24-month time period required to implement the required mitigation measures.

Dazomet-treated articles

Information Note – Treated Articles^{Footnote 4} (September 2022) provides regulatory requirements for articles that have been treated with pesticides.

The import and sale of paper and paper coatings treated with dazomet is permitted during the 24-month implementation period. However, after the 24-month implementation period, the import and sale of dazomet-treated paper and paper coatings will be prohibited.

The import and sale of products treated with dazomet (other than paper and paper coatings) at the unamended label rate and/or without the newly required PPE for professional painters is permitted during the 24-month implementation period. However, after 24 months, the import and sale of products treated at the unamended label rate will be prohibited; all products sold after 24 months must be treated at the new label rate. Additionally, the import and sale of dazomet-treated paint products without the requirement for PPE (for professional painters using airless sprayers) on the label is permitted during the 24-month implementation period. However, all dazomet-treated paint products sold after 24 months must bear the PPE requirements on the label.

Refer to Appendix I for details on specific products impacted by this decision.

Product stewardship/outreach plan

The product stewardship/outreach plan is intended to inform professional painters of the requirement for additional personal protective equipment (coveralls, chemical-resistant gloves, painter's hat and respirator) to mitigate risks when applying paint using airless sprayers. The plan will also have the general goal of increasing awareness of the presence of pesticide preservatives in paint and how to reduce health risks for painters. Health Canada is creating communication materials for this outreach program.

Registrants are required to notify paint manufacturers of the new paint labelling requirements related to PPE for professional painters using an airless sprayer. Paint manufacturers are required to directly label paint cans with the required label statements.

Other information

Any person may file a notice of objection^{Footnote 5} regarding this decision on dazomet and its associated end-use products, used as a preservative in paints, coatings and related uses within 60 days from the date of publication of this Re-evaluation Decision. For more information regarding the basis for objecting (which must be based on scientific grounds), please refer to the Pesticides section of the Canada.ca website (Request a Reconsideration of Decision) or contact Health Canada's Pest Management Information Service.

The relevant confidential test data on which the decision is based (as referenced in PRVD2020-07) are available for public inspection, upon application, in the PMRA's Reading Room. For more information, please contact Health Canada's Pest Management Information Service.

Evaluation Approach

Legislative framework

The Minister of Health's primary objective under the Pest Control Products Act (or the Act) subsection 4(1) is to prevent unacceptable risks to individuals and the environment from the use of pest control products.

As noted in the preamble of the Act, it is in the national interest that the attainment of the objectives of the federal regulatory system continue to be pursued through a scientifically-based national registration system that addresses risks to human health, the environment and value both before and after registration and applies to the regulation of pest control products throughout Canada; and that pest control products with acceptable risk and value be registered for use only if it is shown that their use would be efficacious and if conditions of registration can be established to prevent unacceptable risks to human health and the environment.

For the purposes of the Act, the health or environmental risks of a pest control product are acceptable if there is reasonable certainty that no harm to human health, future generations or the environment will result from exposure to or use of the product, taking into account its conditions of registration as per subsection 2(2) of the Pest Control Products Act.

Risk for the human health and environment, and value are defined under the Act subsection 2(1) as follows:

• health risk, in respect of a pest control product, means the possibility of harm to human health resulting from exposure to or use of the product, taking into account its conditions or proposed conditions of registration.
• environmental risk, in respect of a pest control product, means the possibility of harm to the environment, including its biological diversity, resulting from exposure to or use of the product, taking into account its conditions or proposed conditions of registration.
• value, in respect of a pest control product, means the product's actual or potential contribution to pest management, taking into account its conditions or proposed conditions of registration, and includes the product's (a) efficacy; (b) effect on host organisms in connection with which it is intended to be used; and (c) health, safety and environmental benefits and social and economic impact.

When evaluating the health and environmental risks of a pesticide and determining whether those risks are acceptable, subsection 19(2) of the Pest Control Products Act requires Health Canada to apply a scientifically-based approach. The science-based approach to assessing pesticides considers both the toxicity and the level of exposure of a pesticide in order to fully characterize risk.

Risk and value assessment framework

Health Canada uses a comprehensive body of modern scientific methods and evidence to determine the nature as well as the magnitude of potential risks posed by pesticides. This approach allows for the protection of human health and the environment through the application of appropriate and effective risk management strategies, consistent with the purpose described in the preambular text set out above.

Health Canada's approach to risk and value assessment is outlined in A Framework for Risk Assessment and Risk Management of Pest Control Products.^{Footnote 6} A high-level overview is provided below.

i. Assessing Potential Health Risks

With respect to the evaluation and management of potential health risks, Health Canada's risk assessments follow a structured, predictable process that is consistent with international approaches and the Health Canada Decision-Making Framework for Identifying, Assessing, and Managing Health Risks.^{Footnote 7}

The evaluation of potential health risks begins with a consideration of the toxicological profile of a pesticide to establish reference doses at which no adverse effect is expected and against which the expected exposure is assessed. This includes, where appropriate, the use of uncertainty (protection) factors to provide additional protection that accounts for the variation in sensitivity among members of human population and the uncertainty in extrapolating animal test data to humans. Under certain conditions, the Pest Control Products Act requires the use of another factor to provide additional protection to pregnant women, infants, and children. Other uncertainty factors, such as a database deficiency factor, are considered in specific cases. More details related to the application of the uncertainty factors are provided in SPN2008-01.^{Footnote 8}

Assessments estimate potential health risks to defined populations^{Footnote 9} under specific exposure conditions. They are conducted in the context of the registered conditions of use, such as the use of a pesticide on a particular field crop using specified application rates, methods and equipment. Potential exposure scenarios consider exposures during and after application of the pesticide in occupational or residential settings, food and drinking water exposure, or exposure when interacting with treated pets. Also considered are the anticipated durations (short-, intermediate- or long-term) and routes of exposure (oral, inhalation, or skin contact). In addition, an assessment of health risks must consider available information on aggregate exposure and cumulative effects.

ii. Assessing risks to the environment

With respect to the evaluation of environmental risks, Health Canada's environmental risk assessments follow a structured, tiered approach to determine the likelihood that exposure to a pesticide can cause adverse effects on individual organisms, populations, or ecological systems. This involves screening assessments starting with simple methods, conservative exposure scenarios and sensitive toxicity effects metrics, then moving on, where required, to more refined assessments that can include exposure modelling, monitoring data, results from field or mesocosm studies, and probabilistic risk assessment methods.

The environmental assessment considers both the exposure (environmental fate, chemistry, and behaviour, along with the application rates and methods) and hazard (toxic effects on organisms) of a pesticide. The exposure assessment examines the movement of the pesticide in soil, water, sediments and air, as well as the potential for uptake by plants or animals and transfer through the food web. The possibility for the pesticide to move into sensitive environmental compartments such as groundwater or lakes and rivers, as well as the potential for atmospheric transport, is also examined. The hazard assessment examines effects on a large number of internationally recognized indicator species of plants and animals (terrestrial organisms include invertebrates such as bees, beneficial arthropods, and earthworms, birds, mammals, plants; aquatic organisms include invertebrates, amphibians, fish, plants and algae), and includes considering effects on biodiversity and the food chain. Acute and chronic effects endpoints are derived from laboratory and field studies that characterize the toxic response and the dose–effect relationship of the pesticide.

The characterization of environmental risk requires the integration of information on environmental exposure and effects to identify which, if any, organisms or environmental compartments may be at risk, as well as any uncertainties in characterizing the risk.

iii. Value assessment

Value assessments consist of two components: an assessment of the performance of a pest control product and its benefits.

During re-evaluation, value is examined under current conditions and in light of alternative pest control methods (both chemical and nonchemical) that may have been developed since the pesticide was first registered. An assessment of the benefits associated with the pesticide may also be conducted to demonstrate its value in the current context, and to identify potential alternatives.

Risk management

The outcomes of the assessments of risks to human health and the environment, and the assessment of value, form the basis for identifying risk management strategies. These include appropriate risk mitigation measures and are a key part of decision-making on whether health and environmental risks are acceptable. The development of risk management strategies take place within the context of the pesticide's conditions of registration. Conditions can relate to, among other things, the specific use (for example, application rates, timing, frequency and method of application), personal protective equipment, pre-harvest intervals, restricted entry intervals, buffer zones, spray drift and runoff mitigation measures, handling, manufacture, storage or distribution of a pesticide. If feasible conditions of use that have acceptable risk and value cannot be identified, the pesticide use will not be eligible for registration.

The selected risk management strategy is then implemented as part of the re-evaluation decision. The pesticide registration conditions include legally-binding use directions on the label. Any use in contravention of the label or other specified conditions is illegal under the Pest Control Products Act. Implementation of post-market decisions follow the framework articulated in the Policy on Cancellations and Amendments Following Re-evaluation and Special Review.^{Footnote 10}

Following a decision, continuous oversight activities such as post-market review, monitoring and surveillance, including incident reporting, all play an essential role to help ensure the continued acceptability of risks and value of registered pesticides.

Appendix I Registered material preservative products containing dazomet in Canada as of 6 September 2022